1. Field of the Invention
The present invention relates to a cross roller bearing, and more particularly, to a cross roller bearing wherein split surfaces in the direction that crosses the V-shaped groove of an outer ring are formed in that outer ring.
2. Description of the Prior Art
An example of this type of cross roller bearing is shown in FIGS. 1 through 4. Furthermore, said cross roller bearing is disclosed in, for example, Japanese Patent Publication Laid-Open No. 62-292919.
As shown in the drawings, said cross roller bearing has outer ring 1 and inner ring 2 each formed into the shape of a ring. V-shaped groove la, opening towards the inside, is formed along the circumferential direction in the inner surface of outer ring 1, and V-shaped groove 2a, opening towards the outside, is formed along the circumferential direction in the outer surface of inner ring 2. Outer ring 1 and inner ring 2 are assembled juxtapositioning a plurality of rollers 3 between each of said V-shaped grooves 1a and 2a.
Furthermore, each roller 3 is composed of a cylindrical or spherical roller. As is clear from FIG. 3, rollers 3 are alternately positioned so that the axes of rotation of adjacent rollers cross. In addition, as shown in said drawing, separators 4 are juxtapositioned between each roller 3.
As shown in FIGS. 1 and 4, split surfaces 1b in the direction that crosses V-shaped groove 1a of outer ring 1, and in this case, orthogonal to said V-shaped groove 1a, are formed at one location of said outer ring 1. These split surfaces 1b spread open outer ring 1 at that portion as shown with arrow D in FIG. 4, and are for inserting rollers 3 and separators 4 within the gap formed between inner roller 1 and outer roller 2.
As a result of this constitution in which outer ring 1 is split at one location in the direction that crosses its V-shaped groove la, V-shaped groove 1a of outer ring 1 can be machined with a high degree of precision. Thus, the relative rotational movement of the inner and outer rings performed by means of rollers 3 is performed both smoothly and with high precision. Furthermore, since the above-mentioned split surfaces 1b are formed by breaking, split surfaces 1b completely coincide with each other when said cross roller bearing is incorporated into the revolving portion of a machine and so forth, thus ensuring roundness. In addition, outer ring 1 having this type of constitution is referred to as a single split outer ring.
Despite this, in the cross roller bearing having the constitution as claimed, if even a minute gap forms between the above-mentioned split surfaces 1b, and the load is large, the rotating speed is high or said bearing is used for an extended period of time, this gap accelerates the wear of rollers 3, thus resulting in the disadvantage of greatly impairing a smooth rotating state.
Furthermore, in order to solve this problem, various coupling devices have been proposed to couple those adjacent portions split by split surfaces 1b in order to minimize the above-mentioned gap. However, since the constitutions of these coupling devices are relatively complex, said coupling devices are not always preferable in the case of attempting to reduce the manufacturing cost of the bearing.